WES Western Midstream Partners LP

MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES

This section summarizes the material U.S. federal income tax consequences that may be relevant to prospective common unitholders and is based upon current provisions of the U.S. Internal Revenue Code of 1986, as amended (the “Code”), existing and proposed U.S. Treasury regulations thereunder (the “Treasury Regulations”), and current administrative rulings and court decisions, all of which are subject to change. Changes in these authorities may cause the federal income tax consequences to a prospective common unitholder to vary substantially from those described below, possibly on a retroactive basis. Unless the context otherwise requires, references in this section to “we” or “us” are references to Western Midstream Partners, LP, and references in this section to “units” or “common units” refer to common units representing limited partner interests in Western Midstream Partners, LP.

Legal conclusions contained in this section, unless otherwise noted, are the opinion of Sidley Austin LLP and are based on the accuracy of representations made by us to them for this purpose. However, this section does not address all federal income tax matters that may affect us or our unitholders, such as the application of the alternative minimum tax. This section also does not address local taxes, state taxes, non-U.S. taxes, or other taxes that may be applicable, except to the limited extent that such tax considerations are addressed below under “—State, Local and Other Tax Considerations.” Furthermore, this section focuses on unitholders who are individual citizens or residents of the United States (for federal income tax purposes), who have the U.S. dollar as their functional currency, who use the calendar year as their taxable year, who do not materially participate in the conduct of our business activities and who hold such common units as capital assets (typically, property that is held for investment). This section has limited applicability to corporations (including other entities treated as corporations for federal income tax purposes), partnerships (including other entities treated as partnerships for federal income tax purposes), estates, trusts, non-resident aliens or other unitholders subject to specialized tax treatment, such as tax-exempt entities, non-U.S. persons, individual retirement accounts (“IRAs”), employee benefit plans, real estate investment trusts or mutual funds.

Accordingly, we encourage each prospective unitholder to consult the unitholder’s own tax advisor in analyzing the federal, state, local and non-U.S. tax consequences that are particular to that unitholder resulting from ownership or disposition of our common units and potential changes in applicable tax laws.

No ruling has been requested from the IRS with respect to our classification as a partnership for federal income tax purposes or as to the classification of our partnership and limited liability company operating subsidiaries. We are relying on the opinions and advice of Sidley Austin LLP with respect to the matters described herein. An opinion of counsel represents only that counsel’s best legal judgment and does not bind the Internal Revenue Service (the “IRS”) or a court. Accordingly, the opinions and statements made herein may not be sustained by a court if contested by the IRS. Any such contest of the matters described herein may materially and adversely impact the market for our common units and the prices at which our common units trade. In addition, our costs of any contest with the IRS will be borne indirectly by our unitholders and our general partner because the costs will reduce our cash available for distribution. Furthermore, the tax consequences of an investment in us may be significantly modified by future legislative or administrative changes or court decisions, which may be retroactively applied.

For the reasons described below, Sidley Austin LLP has not rendered an opinion with respect to the following federal income tax issues: (1) the treatment of a common unitholder whose units are the subject of a securities loan (e.g., a loan to a short seller to cover a short sale of units) (please read “—Tax Consequences of Common Unit Ownership-Treatment of Securities Loans”); (2) whether our monthly convention for allocating taxable income and losses is permitted by existing Treasury Regulations (please read “—Disposition of Common Units-Allocations Between Transferors and Transferees”); and (3) whether our method for taking into account Section 743 adjustments is sustainable in certain cases (please read “—Tax Consequences of Common Unit Ownership-Section 754 Election” and “—Uniformity of Units”).

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Partnership Status

We are treated as a partnership for U.S. federal income tax purposes and, therefore, subject to the discussion below under “—Administrative Matters—Information Returns and Audit Procedures”, generally will not be liable for entity-level federal income taxes. Instead, as described below, each of our common unitholders will take into account its respective share of our items of income, gain, loss and deduction in computing its federal income tax liability as if the unitholder had earned such income directly, even if we make no cash distributions to the unitholder. Distributions we make to a common unitholder will not give rise to income or gain taxable to such unitholder, unless the amount of cash distributed exceeds the unitholder’s adjusted tax basis in its common units. (Please read “—Tax Consequences of Common Unit Ownership—Treatment of Distributions” and “—Disposition of Common Units”).

Section 7704 of the Code generally provides that publicly traded partnerships will be treated as corporations for federal income tax purposes. However, if 90% or more of a partnership’s gross income for every taxable year it is publicly traded consists of “qualifying income,” the partnership may continue to be treated as a partnership for federal income tax purposes (the “Qualifying Income Exception”). Qualifying income includes (i) income and gains derived from the exploration, development, mining or production, processing, refining, transportation (including pipelines transporting gas, oil, or products thereof) or the marketing of any “mineral or natural resource”, (ii) interest, (iii) dividends, (iv) real property rents within the meaning of Section 856(d) of the Code, as modified by Section 7704(d)(3) of the Code, (v) gains from the sale or other disposition of real property, and (vi) gains from the sale or other disposition of capital assets (or property described in Section 1231(b) of the Code) held for the production of income that otherwise constitutes qualifying income. We estimate that less than 2% of our current gross income is not qualifying income; however, this estimate could change from time to time.

Sidley Austin LLP is of the opinion that we will be treated as a partnership for federal income tax purposes and each of our partnership and limited liability company operating subsidiaries, except as otherwise identified to Sidley Austin LLP, will be treated as a partnership or will be disregarded as an entity separate from us. In rendering its opinion, Sidley Austin LLP has relied on factual representations made by us and our general partner, including, without limitation:

We believe that these representations have been true in the past, are true as of the date hereof and expect that these representations will continue to be true in the future.

If we fail to meet the Qualifying Income Exception, other than a failure that is determined by the IRS to be inadvertent and that is cured within a reasonable time after discovery (in which case the IRS may also require us to make adjustments with respect to our unitholders or pay other amounts), we will be treated as transferring all of our assets, subject to all of our liabilities, to a newly formed corporation, on the first day of the year in which we fail to meet the Qualifying Income Exception in return for stock in that corporation and then as distributing that stock to our unitholders in liquidation of their interests in us. This deemed contribution and liquidation should not result in the recognition of taxable income by our unitholders or us so long as the aggregate amount of our liabilities does not exceed the adjusted tax basis of our assets. Thereafter, we would be treated as an association taxable as a corporation for federal income tax purposes.

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The present U.S. federal income tax treatment of publicly traded partnerships, including us, or an investment in our common units may be modified by administrative or legislative action or judicial interpretation at any time. For example, from time to time, members of the U.S. Congress have proposed and considered substantive changes to the existing federal income tax laws that would affect publicly traded partnerships, including the elimination of partnership tax treatment for publicly traded partnerships.

It is possible that a change in law could affect us and may be applied retroactively. Any such changes could negatively impact the value of an investment in our common units. If for any reason we are taxable as a corporation in any taxable year, our items of income, gain, loss and deduction would be taken into account by us in determining the amount of our liability for federal income tax, rather than being passed through to our unitholders.

At the state level, several states have been evaluating ways to subject partnerships to entity-level taxation through the imposition of state income, franchise, or other forms of taxation. Imposition of a similar tax on us in the jurisdictions in which we operate or in other jurisdictions to which we may expand could substantially reduce our cash available for distribution to our unitholders.

Our taxation as a corporation would materially reduce the cash available for distribution to unitholders and thus would likely substantially reduce the value of our common units. Any distribution made to a unitholder at a time when we are treated as a corporation would be (i) a taxable dividend to the extent of our current or accumulated earnings and profits, then (ii) a nontaxable return of capital to the extent of the unitholder’s adjusted tax basis in its common units (determined separately for each common unit), and thereafter (iii) taxable capital gain.

The remainder of this discussion is based on the opinion of Sidley Austin LLP that we will be treated as a partnership for federal income tax purposes.

Tax Consequences of Common Unit Ownership

Limited Partner Status

Unitholders of WES who are admitted as limited partners of WES as well as unitholders whose common units are held in street name or by a nominee and who have the right to direct the nominee in the exercise of all substantive rights attendant to the ownership of their common units will be treated as partners of WES for federal income tax purposes. For a discussion related to the risks of losing partner status as a result of securities loans, please read “—Treatment of Securities Loans.” Unitholders who are not treated as partners in us as described above are urged to consult their own tax advisors with respect to the tax consequences applicable to them under their particular circumstances.

Flow-Through of Taxable Income

Subject to the discussion below under “—Entity-Level Collections of Unitholder Taxes” and “—Administrative Matters—Information Returns and Audit Procedures” with respect to payments we may be required to make on behalf of our common unitholders, we will not pay any federal income tax. Rather, each unitholder will be required to report on its federal income tax return each year its share of our income, gains, losses and deductions for our taxable year or years ending with or within its taxable year. Consequently, we may allocate income to a unitholder even if that unitholder has not received a cash distribution.

Basis of Common Units

A unitholder’s tax basis in its common units initially will be the amount paid or treated as paid for those common units increased by the unitholder’s initial allocable share of our liabilities. That basis generally will be

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(i) increased by the unitholder’s share of our income and any increases in such unitholder’s share of our liabilities, and (ii) decreased, but not below zero, by the amount of all distributions to the unitholder, the unitholder’s share of our losses, any decreases in its share of our liabilities, and the amount of any excess business interest allocated to the unitholder. The IRS has ruled that a partner who acquires interests in a partnership in separate transactions must combine those interests and maintain a single adjusted tax basis for all of those interests.

Treatment of Distributions

Distributions made by us to a common unitholder generally will not be taxable to the unitholder, unless such distributions are of cash or marketable securities that are treated as cash and exceed the unitholder’s tax basis in its common units, in which case the unitholder generally will recognize gain taxable in the manner described below under “—Disposition of Common Units.”

Any reduction in a unitholder’s share of our “nonrecourse liabilities” (liabilities for which no partner bears the economic risk of loss) will be treated as a distribution by us of cash to that unitholder. A decrease in a unitholder’s percentage interest in us because of our issuance of additional common units may decrease such unitholder’s share of our nonrecourse liabilities. For purposes of the foregoing, a unitholder’s share of our nonrecourse liabilities generally will be based upon such unitholder’s share of the unrealized appreciation (or depreciation) in our assets, to the extent thereof, with any excess nonrecourse liabilities allocated based on the unitholder’s share of our profits. Please read “—Disposition of Common Units.”

A non-pro rata distribution of money or property (including a deemed distribution as a result of the reallocation of our nonrecourse liabilities described above) may cause a unitholder to recognize ordinary income if the distribution reduces the unitholder’s share of our “unrealized receivables,” including depreciation recapture and substantially appreciated “inventory items,” both as defined in Section 751 of the Code (“Section 751 Assets”). To the extent of such reduction, the unitholder would be deemed to receive its proportionate share of the Section 751 Assets and exchange such assets with us in return for a portion of the non-pro rata distribution. This deemed exchange will generally result in the unitholder’s recognition of ordinary income in an amount equal to the excess of (1) the non-pro rata portion of that distribution over (2) the unitholder’s tax basis (typically zero) in the Section 751 Assets deemed to be relinquished in the exchange.

Limitations on Deductibility of Losses

A common unitholder may not be entitled to deduct the full amount of loss we allocate to it because its share of our losses will be limited to the lesser of (i) the unitholder’s adjusted tax basis in its common units, and (ii) in the case of a unitholder that is an individual, estate, trust or certain types of closely held corporations, the amount for which the unitholder is considered to be “at risk” with respect to our activities. A unitholder will be at risk to the extent of its adjusted tax basis in its common units, reduced by (1) any portion of that basis attributable to the unitholder’s share of our nonrecourse liabilities, (2) any portion of that basis representing amounts otherwise protected against loss because of a guarantee, stop loss agreement or similar arrangement, and (3) any amount of money the unitholder borrows to acquire or hold its common units, if the lender of those borrowed funds owns an interest in us, is related to another unitholder or can look only to the common units for repayment. A unitholder subject to the at risk limitation must recapture losses deducted in previous years to the extent that distributions (including distributions deemed to result from a reduction in a unitholder’s share of nonrecourse liabilities) cause the unitholder’s at risk amount to be less than zero at the end of any taxable year.

Losses disallowed to a unitholder or recaptured as a result of the basis or at risk limitations will carry forward and will be allowable as a deduction in a later year to the extent that the unitholder’s adjusted tax basis or at risk amount, whichever is the limiting factor, is subsequently increased. Upon a taxable disposition of our common units, any gain recognized by a unitholder can be offset by losses that were previously suspended by the at risk limitation but not losses suspended by the basis limitation. Any loss previously suspended by the at risk

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limitation in excess of that gain can no longer be used, and will not be available to offset a unitholder’s salary or active business income.

In addition to the basis and at risk limitations, passive activity loss limitations limit the deductibility of losses incurred by individuals, estates, trusts, some closely held corporations and personal service corporations from “passive activities” (generally, trade or business activities in which the taxpayer does not materially participate). The passive loss limitations are applied separately with respect to each publicly traded partnership. Consequently, any passive losses we generate will be available to offset only passive income generated by us. Passive losses that exceed a unitholder’s share of the passive income we generate may be deducted in full when a unitholder disposes of all of its common units in a fully taxable transaction with an unrelated party. The passive activity loss rules are applied after other applicable limitations on deductions, including the at risk and basis limitations.

For taxpayers other than corporations in taxable years beginning after December 31, 2020, and before January 1, 2029, an “excess business loss” limitation further limits the deductibility of losses by such taxpayers. An excess business loss is the excess (if any) of a taxpayer’s aggregate deductions for the taxable year that are attributable to the trades or businesses of such taxpayer (determined without regard to the excess business loss limitation) over the aggregate gross income or gain of such taxpayer for the taxable year that is attributable to such trades or businesses plus a threshold amount. The current threshold amount is equal to $270,000 or $540,000 for taxpayers filing a joint return. Disallowed excess business losses are treated as a net operating loss carryover to the following tax year. Any losses we generate that are allocated to a unitholder and not otherwise limited by the basis, at risk, or passive loss limitations will be included in the determination of such unitholder’s aggregate trade or business deductions. Consequently, any losses we generate that are not otherwise limited will only be available to offset a unitholder’s other trade or business income plus an amount of non-trade or business income equal to the applicable threshold amount. Thus, except to the extent of the threshold amount, our losses that are not otherwise limited may not offset a unitholder’s non-trade or business income (such as salaries, fees, interest, dividends and capital gains). This excess business loss limitation will be applied after the passive activity loss limitation.

Limitations on Interest Deductions

In general, we are entitled to a deduction for interest paid or accrued on indebtedness properly allocable to our trade or business during our taxable year. However, our deduction for this “business interest” is limited to the sum of our business interest income and 30% of our “adjusted taxable income.” For the purposes of this limitation, our adjusted taxable income is computed without regard to any business interest or business interest income. This limitation is first applied at the partnership level and any deduction for business interest is taken into account in determining our non-separately stated taxable income or loss. Then, in applying this business interest limitation at the partner level, the adjusted taxable income of each of our unitholders is determined without regard to such unitholder’s distributive share of any of our items of income, gain, deduction, or loss and is increased by such unitholder’s distributive share of our excess taxable income, which is generally equal to the excess of 30% of our adjusted taxable income over the amount of our deduction for business interest for a taxable year.

To the extent our deduction for business interest is not limited, we will allocate the full amount of our deduction for business interest among our unitholders in accordance with their percentage interests in us. To the extent our deduction for business interest is limited, the amount of any disallowed deduction for business interest will also be allocated to each unitholder in accordance with their percentage interest in us, but such amount of “excess business interest” will not be currently deductible. Subject to certain limitations and adjustments to a unitholder’s basis in its common units, this excess business interest may be carried forward and deducted by a unitholder in a future taxable year. Further, a unitholder’s basis in his or her common units will generally be increased by the amount of any excess business interest upon a disposition of such common units.

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In addition to this limitation on the deductibility of a partnership’s business interest, the deductibility of a non-corporate taxpayer’s “investment interest expense” is generally limited to the amount of that taxpayer’s “net investment income.” Investment interest expense includes:

The computation of a unitholder’s investment interest expense will take into account interest on any margin account borrowing or other loan incurred to purchase or carry a unit. Net investment income includes gross income from property held for investment and amounts treated as portfolio income under the passive loss rules, less deductible expenses, other than interest, directly connected with the production of investment income. Net investment income does not include qualified dividend income (if applicable) or gains attributable to the disposition of property held for investment. A unitholder’s share of a publicly traded partnership’s portfolio income and, according to the IRS, net passive income will be treated as investment income for purposes of the investment interest expense limitation.

Entity-Level Collections of Unitholder Taxes

If we are required or elect under applicable law to pay any federal, state, local or non-U.S. tax on behalf of any current or former unitholder or our general partner, our Partnership Agreement authorizes us to treat the payment as a distribution of cash to the relevant unitholder or general partner. Where the tax is payable on behalf of all unitholders or we cannot determine the specific unitholder on whose behalf the tax is payable, our Partnership Agreement authorizes us to treat the payment as a distribution to all current unitholders. We are authorized to amend our Partnership Agreement in the manner necessary to maintain uniformity of intrinsic tax characteristics of common units and to adjust later distributions, so that after giving effect to these distributions, the priority and characterization of distributions otherwise applicable under our Partnership Agreement is maintained as nearly as is practicable. Payments by us as described above could give rise to an overpayment of tax on behalf of a unitholder, in which event the unitholder may be entitled to claim a refund of the overpayment amount. Please read “—Administrative Matters—Information Returns and Audit Procedures”. Common unitholders are urged to consult their tax advisors to determine the consequences to them of any tax payment we make on their behalf.

Allocation of Income, Gain, Loss and Deduction

Our items of income, gain, loss and deduction generally will be allocated amongst our unitholders and our general partner in accordance with their percentage interests in us.

Specified items of our income, gain, loss and deduction will be allocated under Section 704(c) of the Code (or the principles of Section 704(c) of the Code) to account for any difference between the adjusted tax basis and fair market value of our assets at the time such assets are contributed to us and at the time of any subsequent offering of our common units (a “Book-Tax Disparity”). As a result, the federal income tax burden associated with any Book-Tax Disparity immediately prior to an offering will be borne by our partners holding interests in us prior to such offering. In addition, items of recapture income will be specially allocated to the extent possible (subject to the limitations described above) to the unitholder who was allocated the deduction giving rise to that recapture income in order to minimize the recognition of ordinary income by other unitholders.

An allocation of items of our income, gain, loss or deduction, other than an allocation required by the Code to eliminate a Book-Tax Disparity, will be given effect for federal income tax purposes in determining a unitholder’s share of an item of income, gain, loss or deduction only if the allocation has “substantial economic

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effect.” In any other case, a unitholder’s share of an item will be determined on the basis of the unitholder’s interest in us, which will be determined by taking into account all the facts and circumstances, including (i) the unitholder’s relative contributions to us, (ii) the interests of all the partners in profits and losses, (iii) the interest of all the partners in cash flow and (iv) the rights of all the partners to distributions of capital upon liquidation. Sidley Austin LLP is of the opinion that, with the exception of the issues described in “— Section 754 Election” and “— Disposition of Common Units — Allocations Between Transferors and Transferees,” allocations of income, gain, loss or deduction under our Partnership Agreement will be given effect for federal income tax purposes.

Treatment of Securities Loans

A unitholder whose common units are the subject of a securities loan (for example, a loan to a “short seller” to cover a short sale of common units) may be treated as having disposed of those common units. If so, such unitholder would no longer be treated for tax purposes as a partner with respect to those common units during the period of the loan and may recognize gain or loss as a result of such deemed disposition. As a result, during this period (i) any of our income, gain, loss or deduction allocated to those common units would not be reportable by the lending unitholder, and (ii) any cash distributions received by the lending unitholder as to those common units may be treated as ordinary taxable income.

Due to a lack of controlling authority, Sidley Austin LLP has not rendered an opinion regarding the tax treatment of a unitholder that enters into a securities loan with respect to its common units. Unitholders desiring to assure their status as partners and avoid the risk of income recognition from a loan of their common units are urged to modify any applicable brokerage account agreements to prohibit their brokers from borrowing and lending their common units. The IRS has announced that it is studying issues relating to the tax treatment of short sales of partnership interests. Please read “—Disposition of Common Units—Recognition of Gain or Loss.”

Tax Rates

Under current law, the highest marginal federal income tax rates for individuals applicable to ordinary income and long-term capital gains (generally, gains from the sale or exchange of certain investment assets held for more than one year) are 37% and 20%, respectively. These rates are subject to change by new legislation at any time.

In addition, a 3.8% net investment income tax applies to certain net investment income earned by individuals, estates, and trusts. For these purposes, net investment income generally includes a unitholder’s allocable share of our income and gain realized by a unitholder from a sale of common units (without taking into account the 20% deduction for qualified business income discussed below). In the case of an individual, the tax will be imposed on the lesser of (i) the unitholder’s net investment income from all investments, or (ii) the amount by which the unitholder’s modified adjusted gross income exceeds $250,000 (if the unitholder is married and filing jointly or a surviving spouse), $125,000 (if the unitholder is married and filing separately) or $200,000 (if the unitholder is unmarried or in any other case). In the case of an estate or trust, the tax will be imposed on the lesser of (i) undistributed net investment income, or (ii) the excess adjusted gross income over the dollar amount at which the highest income tax bracket applicable to an estate or trust begins.

For taxable years beginning after December 31, 2017 and ending on or before December 31, 2025, an individual unitholder is entitled to a deduction equal to 20% of his or her allocable share of our “qualified business income”, subject to limitations. For purposes of this deduction, our “qualified business income” is equal to the sum of:

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Section 754 Election

We have made the election permitted by Section 754 of the Code that permits us to adjust the tax basis in each of our assets as to specific purchasers of our common units under Section 743(b) of the Code to reflect the common unit purchase price upon subsequent purchases of common units and to adjust the tax basis in each of our assets under Section 734(b) of the Code in the event of our repurchase of common units. That election is irrevocable without the consent of the IRS. The Section 743(b) adjustment separately applies to a unitholder who purchases common units from another unitholder based upon the values and adjusted tax basis of each of our assets at the time of the relevant unit purchase, and the adjustment will reflect the purchase price paid. The Section 743(b) adjustment does not apply to a person who purchases common units directly from us. For purposes of this discussion, a unitholder’s basis in our assets will be considered to have two components: (1) its share of the tax basis in our assets as to all unitholders and (2) its Section 743(b) adjustment to that tax basis (which may be positive or negative).

Subject to certain limitations, a Section 743(b) adjustment may create additional depreciable basis that is eligible for bonus depreciation under Section 168(k) to the extent the adjustment is attributable to depreciable property and not to goodwill or real property. However, because we may not be able to determine whether transfers of our units satisfy all of the eligibility requirements and due to other limitations regarding administrability, we may elect out of the bonus depreciation provisions of Section 168(k) with respect to basis adjustments under Section 743(b).

Under our Partnership Agreement, we are authorized to take a position to preserve the uniformity of common units even if that position is not consistent with applicable Treasury Regulations. A literal application of Treasury Regulations governing a Section 743(b) adjustment attributable to properties depreciable under Section 167 of the Code may give rise to differences in the taxation of unitholders purchasing common units from us and unitholders purchasing from other unitholders. If we have any such properties, we intend to adopt methods employed by other publicly traded partnerships to preserve the uniformity of common units, even if inconsistent with existing Treasury Regulations, and Sidley Austin LLP has not opined on the validity of this approach. Please read “—Uniformity of Common Units.”

The IRS may challenge the positions we adopt with respect to depreciating or amortizing the Section 743(b) adjustment to preserve the uniformity of common units due to the lack of controlling authority. Because a unitholder’s adjusted tax basis in its common units is reduced by its share of our items of deduction or loss, any position we take that understates deductions will overstate a unitholder’s tax basis in its common units, and may cause the unitholder to understate gain or overstate loss on any sale of such common units. Please read “— Disposition of Common Units — Recognition of Gain or Loss.” If a challenge to such treatment were sustained, the gain from the sale of common units may be increased without the benefit of additional deductions.

The calculations involved in the Section 754 election are complex and are made on the basis of assumptions as to the value of our assets and other matters. The IRS could seek to reallocate some or all of any Section 743(b) adjustment we allocated to our assets subject to depreciation to goodwill or nondepreciable assets. Goodwill, as an intangible asset, is generally amortizable over a longer period of time or under a less accelerated method than our tangible assets. We cannot assure any unitholder that the determinations we make will not be successfully challenged by the IRS or that the resulting deductions will not be reduced or disallowed altogether. Should the IRS require a different tax basis adjustment to be made, and should, in our opinion, the expense of compliance exceed the benefit of the election, we may seek permission from the IRS to revoke our Section 754 election. If permission is granted, a subsequent purchaser of common units may be allocated more income than it would have been allocated had the election not been revoked.

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Tax Treatment of Operations

Accounting Method and Taxable Year

We use the year ending December 31 as our taxable year and the accrual method of accounting for federal income tax purposes. Each unitholder will be required to include in its tax return its share of our income, gain, loss and deduction for each taxable year ending within or with its taxable year. In addition, a unitholder who has a taxable year ending on a date other than December 31 and who disposes of all of its common units following the close of our taxable year but before the close of its taxable year must include its share of our income, gain, loss and deduction in income for its taxable year, with the result that it will be required to include in income for its taxable year its share of more than twelve months of our income, gain, loss and deduction. Please read “—Disposition of Common Units—Allocations Between Transferors and Transferees.”

Tax Basis, Depreciation and Amortization

The tax basis of each of our assets will be used for purposes of computing depreciation and cost recovery deductions and, ultimately, gain or loss on the disposition of these assets. To the extent allowable, we may use the depreciation and cost recovery methods, including bonus depreciation to the extent available, that will result in the largest deductions being taken in the early years after assets subject to these allowances are placed in service. Property we subsequently acquire or construct may be depreciated using accelerated methods permitted by the Code.

If we dispose of depreciable property by sale, foreclosure or otherwise, all or a portion of any gain, determined by reference to the amount of depreciation deductions previously taken, may be subject to the recapture rules and taxed as ordinary income rather than capital gain. Similarly, a unitholder who has taken cost recovery or depreciation deductions with respect to property we own will likely be required to recapture some or all of those deductions as ordinary income upon a sale of its interest in us. Please read “—Tax Consequences of Common Unit Ownership—Allocation of Income, Gain, Loss and Deduction” and “—Disposition of Common Units – Recognition of Gain or Loss.”

The costs we incur in offering and selling our common units (called “syndication expenses”) must be capitalized and cannot be deducted currently, ratably or upon our termination. While there are uncertainties regarding the classification of certain costs as organization expenses, which may be amortized by us, and as syndication expenses, which may not be amortized by us, the underwriting discounts and commissions we incur will be treated as syndication expenses. Please read “Disposition of Common Units – Recognition of Gain or Loss.”

Valuation and Tax Basis of Each of Our Properties

The federal income tax consequences of the ownership and disposition of common units will depend in part on our estimates of the relative fair market values and the tax basis of each of our assets. Although we may from time to time consult with professional appraisers regarding valuation matters, we will make many of the relative fair market value estimates and determinations of tax basis ourselves. These estimates and determinations of tax basis are subject to challenge and will not be binding on the IRS or the courts. If the estimates of fair market value or tax basis are later found to be incorrect, the character and amount of items of income, gain, loss or deduction previously reported by common unitholders could change, and common unitholders could be required to adjust their tax liability for prior years and incur interest and penalties with respect to those adjustments.

Disposition of Common Units

Recognition of Gain or Loss

A unitholder will be required to recognize gain or loss on a sale or exchange of a common unit equal to the difference, if any, between the unitholder’s amount realized and the adjusted tax basis in the common unit sold

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(taking into account any basis adjustments attributable to previously disallowed interest deductions). A common unitholder’s amount realized generally will equal the sum of the cash and the fair market value of other property it receives plus its share of our nonrecourse liabilities with respect to the common unit sold or exchanged. Because the amount realized includes a unitholder’s share of our nonrecourse liabilities, the gain recognized on the sale or exchange of a common unit could result in a tax liability in excess of any cash received from such sale or exchange.

Except as noted below, gain or loss recognized by a unitholder on the sale or exchange of a common unit held for more than one year generally will be taxable as long-term capital gain or loss. However, gain or loss recognized on the disposition of common units will be separately computed and taxed as ordinary income or loss under Section 751 of the Code to the extent attributable to Section 751 Assets, such as depreciation recapture and our “inventory items,” regardless of whether such inventory item has substantially appreciated in value. Ordinary income attributable to Section 751 Assets may exceed net taxable gain realized on the sale or exchange of a common unit and may be recognized even if there is a net taxable loss realized on the sale or exchange of a common unit. Thus, a unitholder may recognize both ordinary income and capital gain or loss upon a sale or exchange of a common unit. Net capital loss may offset capital gains and, in the case of individuals, up to $3,000 of ordinary income per year.

For purposes of calculating gain or loss on the sale or exchange of a common unit, the unitholder’s adjusted tax basis will be adjusted by its allocable share of our income or loss in respect of its common unit for the year of the sale. Furthermore, as described above, the IRS has ruled that a partner who acquires interests in a partnership in separate transactions must combine those interests and maintain a single adjusted tax basis for all those interests. Upon a sale or other disposition of less than all of those interests, a portion of that tax basis must be allocated to the interests sold using an “equitable apportionment” method, which generally means that the tax basis allocated to the interest sold equals an amount that bears the same relation to the partner’s tax basis in its entire interest in the partnership as the value of the interest sold bears to the value of the partner’s entire interest in the partnership.

Treasury Regulations under Section 1223 of the Code allow a selling unitholder who can identify common units transferred with an ascertainable holding period to elect to use the actual holding period of the common units transferred. Thus, according to the ruling discussed in the paragraph above, a unitholder will be unable to select high or low basis common units to sell or exchange as would be the case with corporate stock, but, according to the Treasury Regulations, such unitholder may designate specific common units sold for purposes of determining the holding period of the common units transferred. A unitholder electing to use the actual holding period of any common unit transferred must consistently use that identification method for all subsequent sales or exchanges of our common units. A unitholder considering the purchase of additional common units or a sale or exchange of common units purchased in separate transactions is urged to consult its tax advisor as to the possible consequences of this ruling and application of the Treasury Regulations.

Specific provisions of the Code affect the taxation of some financial products and securities, including partnership interests, by treating a taxpayer as having sold an “appreciated” financial position, including a partnership interest with respect to which gain would be recognized if it were sold, assigned or terminated at its fair market value, in the event the taxpayer or a related person enters into:

Moreover, if a taxpayer has previously entered into a short sale, an offsetting notional principal contract or a futures or forward contract with respect to the partnership interest, the taxpayer will be treated as having sold that position if the taxpayer or a related person then acquires the partnership interest or substantially identical property. The Secretary of the Treasury is authorized to issue Treasury Regulations that treat a taxpayer that

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enters into transactions or positions that have substantially the same effect as the preceding transactions as having constructively sold the financial position. Please read “—Tax Consequences of Common Unit Ownership—Treatment of Securities Loans.”

Allocations Between Transferors and Transferees

In general, our taxable income or loss will be determined annually, will be prorated on a monthly basis and will be subsequently apportioned among the unitholders in proportion to the number of common units owned by each of them as of the opening of the applicable exchange on the first business day of the month (the “Allocation Date”). Nevertheless, we allocate certain deductions for depreciation of capital additions based upon the date the underlying property is placed in service, and gain or loss realized on a sale or other disposition of our assets or, in the discretion of the general partner, any other extraordinary item of income, gain, loss or deduction will be allocated among the unitholders on the Allocation Date in the month in which such income, gain, loss or deduction is recognized. As a result, a unitholder transferring common units may be allocated income, gain, loss and deduction realized after the date of transfer.

Although simplifying conventions are contemplated by the Code and most publicly traded partnerships use similar simplifying conventions, existing Treasury Regulations do not specifically authorize the use of the proration method we have adopted. Accordingly, Sidley Austin LLP is unable to opine on the validity of this method of allocating income and deductions between transferee and transferor unitholders. If the IRS determines that this method is not allowed under the Treasury Regulations our taxable income or losses could be reallocated among our unitholders. Under our Partnership Agreement, we are authorized to revise our method of allocation between transferee and transferor unitholders, as well as among unitholders whose interests vary during a taxable year, to conform to a method permitted under the Treasury Regulations.

A unitholder who disposes of common units prior to the record date set for a cash distribution for that quarter will be allocated items of our income, gain, loss and deduction attributable to the month of disposition (and any other month during the quarter to which such cash distribution relates and the holder held common units on the first day of such month) but will not be entitled to receive a cash distribution for that period.

Notification Requirements

A unitholder who sells or exchanges any of its common units is generally required to notify us in writing of that transaction within 30 days after the transaction (or, if earlier, January 15 of the year following the transaction in the case of a seller). Upon receiving such notifications, we are required to notify the IRS of the transaction and to furnish specified information to the transferor and transferee. Failure to notify us of a transfer of common units may, in some cases, lead to the imposition of penalties. However, these reporting requirements do not apply to a sale by an individual who is a citizen of the United States and who effects the sale or exchange through a broker who will satisfy such requirements.

Uniformity of Common Units

Because we cannot match transferors and transferees of common units and for other reasons, we must maintain uniformity of the economic and tax characteristics of the common units to a purchaser of these common units. As a result of the need to preserve uniformity, we may be unable to completely comply with a number of federal income tax requirements. Any non-uniformity could have a negative impact on the value of our common units. Please read “—Tax Consequences of Common Unit Ownership—Section 754 Election.”

Our Partnership Agreement permits our general partner to take positions in filing our tax returns that preserve the uniformity of our common units. These positions may include reducing the depreciation, amortization or loss deductions to which a unitholder would otherwise be entitled or reporting a slower amortization of Section 743(b) adjustments for some unitholders than that to which they would otherwise be entitled. Sidley Austin LLP is unable to opine as to the validity of such filing positions.

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A unitholder’s adjusted tax basis in common units is reduced by its share of our deductions (whether or not such deductions were claimed on an individual income tax return) so that any position that we take that understates deductions will overstate the unitholder’s basis in its common units, and may cause the unitholder to understate gain or overstate loss on any sale of such common units. Please read “— Disposition of Common Units—Recognition of Gain or Loss” and “—Tax Consequences of Common Unit Ownership—Section 754 Election” above. The IRS may challenge one or more of any positions we take to preserve the uniformity of our common units. If such a challenge were sustained, the uniformity of common units might be affected, and, under some circumstances, the gain from the sale of our common units might be increased without the benefit of additional deductions.

Tax-Exempt Organizations and Other Investors

Ownership of our common units by employee benefit plans and other tax-exempt organizations, as well as by non-resident alien individuals, non-U.S. corporations and other non-U.S. persons (collectively, “Non-U.S. Unitholders”) raises issues unique to those investors and, as described below, may have substantial adverse tax consequences to them. Prospective unitholders that are tax-exempt entities or Non-U.S. Unitholders should consult their tax advisors before investing in our common units.

Employee benefit plans and most other tax-exempt organizations, including IRAs and other retirement plans, are subject to federal income tax on unrelated business taxable income. Virtually all of our income will be unrelated business taxable income and will be taxable to a tax-exempt unitholder.

Non-U.S. Unitholders will be considered to be engaged in business in the United States because of their ownership of our common units and will be deemed to conduct such activities through a permanent establishment in the United States within the meaning of an applicable tax treaty. Consequently, Non-U.S. Unitholders will be required to file federal tax returns to report their share of our income, gain, loss or deduction and pay federal income tax on their share of our net income or gain. Moreover, under rules applicable to publicly traded partnerships, distributions to Non-U.S. Unitholders are subject to withholding at the highest applicable effective tax rate. Moreover, distributions to Non-U.S. Unitholders are subject to withholding at the highest applicable effective tax rate. In addition, distributions to non-U.S. Unitholders will also be subject to a 10% withholding tax on the amount of any distribution in excess of our cumulative net income. The determination of cumulative net income is complex and unclear in certain respects, and we intend to treat all of our distributions as being in excess of our cumulative net income for such purposes and subject to the additional 10% withholding tax. Accordingly, distributions to non-U.S. persons will be subject to a combined withholding tax rate equal to the sum of the highest applicable effective tax rate and 10%. Each Non-U.S. Unitholder must obtain a taxpayer identification number from the IRS and submit that number to our transfer agent on a Form W-8BEN or W-8BEN-E (or other applicable or successor form) in order to obtain credit for these withholding taxes.

In addition, if a Non-U.S. Unitholder is classified as a non-U.S. corporation, it will be treated as engaged in a United States trade or business and may be subject to the U.S. branch profits tax at a rate of 30%, in addition to regular U.S. federal income tax, on its share of our income and gain as adjusted for changes in the foreign corporation’s “U.S. net equity” to the extent reflected in the corporation’s earnings and profits. That tax may be reduced or eliminated by an income tax treaty between the United States and the country in which the foreign corporate unitholder is a “qualified resident.” In addition, this type of unitholder is subject to special information reporting requirements under Section 6038C of the Code.

A Non-U.S. Unitholder who sells or otherwise disposes of a common unit will be subject to U.S. federal income tax on gain realized from the sale or disposition of that common unit to the extent the gain is effectively connected with a U.S. trade or business of the Non-U.S. Unitholder. Gain realized by a Non-U.S. Unitholder from the sale of its interest in a partnership that is engaged in a trade or business in the United States will be considered to be “effectively connected” with a U.S. trade or business to the extent that gain that would be recognized upon a sale by the partnership of all of its assets would be “effectively connected” with a U.S. trade

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or business. Thus, part or all of a Non-U.S. Unitholder’s gain from the sale or other disposition of our common units would be treated as effectively connected with a unitholder’s indirect U.S. trade or business constituted by its investment in us and would be subject to U.S. federal income tax. As a result of the effectively connected income rules described above, the exclusion from U.S. taxation under the Foreign Investment in Real Property Tax Act for gain from the sale of partnership common units regularly traded on an established securities market will not prevent a Non-U.S. Unitholder from being subject to U.S. federal income tax on gain from the sale or disposition of its common units to the extent such gain is effectively connected with a U.S. trade or business. We expect substantially all of the gain from the sale or disposition of our common units to be treated as effectively connected with a U.S. trade or business.

Moreover, the transferee of an interest in a partnership that is engaged in a U.S. trade or business is generally required to withhold 10% of the amount realized by the transferor unless the transferor certifies that it is not a foreign person. Treasury regulations provide that the “amount realized” on a transfer of an interest in a publicly traded partnership, such as our common units, will generally be the amount of gross proceeds paid to the broker effecting the applicable transfer on behalf of the transferor. Treasury regulations and recent Treasury guidance further provide that these rules will not apply to transfers of interests in a publicly traded partnership occurring prior to January 1, 2023. Thereafter, the obligation to withhold on a transfer of interests in a publicly traded partnership that is effected through a broker is imposed on the transferor’s broker. Current and prospective Non-U.S. Unitholders should consult their tax advisors regarding the impact of these rules on an investment in our common units.

Administrative Matters

Information Returns and Audit Procedures

We intend to furnish to each unitholder, within 90 days after the close of each taxable year, specific tax information, including a Schedule K-1, which describes its share of our income, gain, loss and deduction for our preceding taxable year. In preparing this information, which will not be reviewed by counsel, we will take various accounting and reporting positions, some of which have been mentioned earlier, to determine each unitholder’s share of income, gain, loss and deduction. We cannot assure our common unitholders that those positions will yield a result that conforms to all of the requirements of the Code, Treasury Regulations or administrative interpretations of the IRS.

The IRS may audit our federal income tax information returns. Neither we nor Sidley Austin LLP can assure prospective unitholders that the IRS will not successfully challenge the positions we adopt, and such a challenge could adversely affect the value of our common units. Adjustments resulting from an IRS audit may require each unitholder to adjust a prior year’s tax liability, and may result in an audit of the unitholder’s own return. Any audit of a unitholder’s return could result in adjustments unrelated to our returns.

Publicly traded partnerships are treated as entities separate from their owners for purposes of federal income tax audits, judicial review of administrative adjustments by the IRS and tax settlement proceedings. The tax treatment of partnership items of income, gain, loss and deduction is determined in a partnership proceeding rather than in separate proceedings for each of the partners. Pursuant to the Bipartisan Budget Act of 2015, for taxable years beginning after December 31, 2017, if the IRS makes audit adjustments to our income tax returns, it may assess and collect any taxes (including any applicable penalties and interest) resulting from such audit adjustment directly from us, unless we elect to have our general partner, unitholders and former unitholders take any audit adjustment into account in accordance with their interests in us during the taxable year under audit. Similarly, for such taxable years, if the IRS makes audit adjustments to income tax returns filed by an entity in which we are a member or partner, it may assess and collect any taxes (including penalties and interest) resulting from such audit adjustment directly from such entity.

Generally, we expect to elect to have our general partner, unitholders and former unitholders take any such audit adjustment into account in accordance with their interests in us during the taxable year under audit, but

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there can be no assurance that such election will be effective in all circumstances. If we are unable or if it is not economical to have our general partner, unitholders and former unitholders take such audit adjustment into account in accordance with their interests in us during the taxable year under audit, then our current unitholders may bear some or all of the tax liability resulting from such audit adjustment, even if such unitholders did not own our common units during the taxable year under audit. If, as a result of any such audit adjustment, we are required to make payments of taxes, penalties or interest, we may require out unitholders and former unitholder to reimburse us for such taxes (including any applicable penalties or interest) or, if we bear such payment directly, our cash available for distribution to our unitholders might be substantially reduced. These rules are not applicable for taxable years beginning on or prior to December 31, 2017. Congress has proposed changes to the Bipartisan Budget Act, and we anticipate that amendments may be made. Accordingly, the manner in which these rules may apply to us in the future is uncertain.

Additionally, pursuant to the Bipartisan Budget Act of 2015, the Code will no longer require that we designate a Tax Matters Partner. Instead, for taxable years beginning after December 31, 2017, we will be required to designate a partner, or other person, with a substantial presence in the United States as the partnership representative (“Partnership Representative”). The Partnership Representative will have the sole authority to act on our behalf for purposes of, among other things, federal income tax audits and judicial review of administrative adjustments by the IRS. If we do not make such a designation, the IRS can select any person as the Partnership Representative. We currently anticipate that we will designate our general partner as the Partnership Representative. Further, any actions taken by us or by the Partnership Representative on our behalf with respect to, among other things, federal income tax audits and judicial review of administrative adjustments by the IRS, will be binding on us and all of our unitholders.

Additional Withholding Requirements

Withholding taxes may apply to certain types of payments made to “foreign financial institutions” (as specially defined in the Code) and certain other non-U.S. entities. Specifically, a 30% withholding tax may be imposed on withholdable payments, including interest, dividends and other fixed or determinable annual or periodic gains, profits and income from sources within the United States (“FDAP Income”) paid to a foreign financial institution or to a “non-financial foreign entity” (as specially defined in the Code), unless (i) the foreign financial institution undertakes certain diligence and reporting, (ii) the non-financial foreign entity either certifies it does not have any substantial U.S. owners or furnishes identifying information regarding each substantial U.S. owner or (iii) the foreign financial institution or non-financial foreign entity otherwise qualifies for an exemption from these rules. While withholdable payments would have originally included payments of gross proceeds from the sale or other disposition of any property of a type which could produce interest or dividends from sources within the United States (“Gross Proceeds”) on or after January 1, 2019, proposed Treasury Regulations provide that such payments of Gross Proceeds do not constitute withholdable payments. Taxpayers may rely generally on these proposed Treasury Regulations until they are revoked or final Treasury Regulations are issued. If the payee is a foreign financial institution and is subject to the diligence and reporting requirements in clause (i) above, it must enter into an agreement with the U.S. Department of the Treasury requiring, among other things, that it undertake to identify accounts held by certain U.S. persons or U.S.-owned foreign entities, annually report certain information about such accounts, and withhold 30% on payments to noncompliant foreign financial institutions and certain other account holders. Foreign financial institutions located in jurisdictions that have an intergovernmental agreement with the United States governing these requirements may be subject to different rules.

To the extent we have FDAP Income that is not treated as effectively connected with a U.S. trade or business (please read “—Tax-Exempt Organizations and Other Investors”), a unitholder that is a foreign financial institution or certain other non-U.S. entity, or a person that holds its common units through such foreign entities, may be subject to withholding on distributions they receive from us, or its distributive share of our income, pursuant to the rules described above.

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Each prospective unitholder should consult its own tax advisors regarding the potential application of these withholding provisions to its investment in our common units.

Nominee Reporting

Persons who hold an interest in us as a nominee for another person are required to furnish to us:

Each broker and financial institution is required to furnish additional information, including whether such broker or financial institution is a U.S. person and specific information on any common units such broker or financial institution acquires, holds or transfers for its own account. A penalty per failure, with a significant maximum penalty per calendar year, is imposed by the Code for failure to report that information to us. The nominee is required to supply the beneficial owner of our common units with the information furnished to us.

Accuracy-Related Penalties

Certain penalties may be imposed as a result of an underpayment of tax that is attributable to one or more specified causes, including negligence or disregard of rules or regulations, substantial understatements of income tax and substantial valuation misstatements. No penalty will be imposed, however, for any portion of an underpayment if it is shown that there was a reasonable cause for the underpayment of that portion and that the taxpayer acted in good faith regarding the underpayment of that portion. We do not anticipate that any accuracy-related penalties will be assessed against us.

State, Local and Other Tax Considerations

In addition to federal income taxes, unitholders may be subject to other taxes, including state and local income taxes, unincorporated business taxes and estate, inheritance or intangibles taxes that may be imposed by the various jurisdictions in which we conduct business or own property now or in the future or in which the unitholder is a resident. We conduct business or own property in many states in the United States. Some of these states may impose an income tax on individuals, corporations and other entities. As we make acquisitions or expand our business, we may own property or conduct business in additional states that impose a personal income tax. Although an analysis of those various taxes is not presented here, each prospective unitholder should consider the potential impact of such taxes on its investment in us.

A unitholder may be required to file income tax returns and pay income taxes in some or all of the jurisdictions in which we do business or own property, though such unitholder may not be required to file a return and pay taxes in certain jurisdictions because its income from such jurisdictions falls below the jurisdiction’s filing and payment requirement. Further, a unitholder may be subject to penalties for a failure to comply with any filing or payment requirement applicable to such unitholder. Some of the jurisdictions may require us, or we may elect, to withhold a percentage of income from amounts to be distributed to a unitholder

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who is not a resident of the jurisdiction. Withholding, the amount of which may be greater or less than a particular unitholder’s income tax liability to the jurisdiction, generally does not relieve a nonresident unitholder from the obligation to file an income tax return.

IT IS THE RESPONSIBILITY OF EACH UNITHOLDER TO INVESTIGATE THE LEGAL AND TAX CONSEQUENCES, UNDER THE LAWS OF PERTINENT JURISDICTIONS, OF HIS INVESTMENT IN US. WE STRONGLY RECOMMEND THAT EACH PROSPECTIVE UNITHOLDER CONSULT, AND DEPEND UPON, ITS OWN TAX COUNSEL OR OTHER ADVISOR WITH REGARD TO THOSE MATTERS. FURTHER, IT IS THE RESPONSIBILITY OF EACH UNITHOLDER TO FILE ALL STATE, LOCAL AND NON-U.S., AS WELL AS U.S. FEDERAL TAX RETURNS THAT MAY BE REQUIRED OF IT. SIDLEY AUSTIN LLP HAS NOT RENDERED AN OPINION ON THE STATE, LOCAL, ALTERNATIVE MINIMUM TAX OR NON-U.S. TAX CONSEQUENCES OF AN INVESTMENT IN US.

Tax Consequences of Ownership of WES Preferred Units

A description of the material U.S. federal income tax consequences of the acquisition, ownership and disposition of WES preferred units will be set forth in the prospectus supplement relating to the offering of WES preferred units.

Tax Consequences of Ownership of WES Operating Debt Securities

A description of the material U.S. federal income tax consequences of the acquisition, ownership and disposition of debt securities will be set forth in the prospectus supplement relating to the offering of debt securities.

INVESTMENT IN WES COMMON UNITS, WES PREFERRED UNITS OR WES OPERATING DEBT SECURITIES BY EMPLOYEE BENEFIT PLANS

The following is a summary of certain considerations associated with an investment in WES common units, WES preferred units or WES Operating debt securities by employee benefit plans that are subject to the fiduciary responsibility and prohibited transaction provisions of the Employee Retirement Income Security Act of 1974, as amended (“ERISA”), the prohibited transaction restrictions imposed by Section 4975 of the Code or provisions under any federal, state, local, non-U.S. or other laws or regulations that are similar to such provisions of the Code or ERISA (collectively, “Similar Laws”). As used herein, the term “employee benefit plan” includes, but is not limited to, qualified pension, profit-sharing and stock bonus plans, certain Keogh plans, certain simplified employee pension plans and tax deferred annuities, individual retirement accounts (“IRAs”) and other arrangements established or maintained by an employer or employee organization, and entities whose underlying assets are considered to include “plan assets” of such plans, accounts and arrangements.

This summary is based on the provisions of ERISA and the Code (and related regulations and administrative and judicial interpretations) as of the date of this prospectus. This summary does not purport to be complete and future legislation, court decisions, administrative regulations, rulings or pronouncements could significantly modify the requirements summarized below. Any of these changes may be retroactive and may thereby apply to transactions entered into prior to the date of their enactment or release.

General Fiduciary Matters

ERISA and the Code impose certain duties on persons who are fiduciaries of an employee benefit plan that is subject to Title I of ERISA or Section 4975 of the Code (an “ERISA Plan”) and prohibit certain transactions

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involving the assets of an ERISA Plan and its fiduciaries or other interested parties. Under ERISA and Section 4975 of the Code, any person who exercises any discretionary authority or control over the administration of an ERISA Plan or the management or disposition of the assets of an ERISA Plan, or who renders investment advice for a fee or other compensation to an ERISA Plan, is generally considered to be a fiduciary of the ERISA Plan.

Governmental plans (as defined in Section 3(32) of ERISA) and certain church plans (as defined in Section 3(33) of ERISA) and non-U.S. plans (as defined in Section 4(b)(4) of ERISA), while generally not subject to the fiduciary responsibility provisions of ERISA or the provisions of Section 4975 of the Code, may nevertheless be subject to local, state or other federal or non-U.S. laws that are substantially similar to ERISA and the Code. Fiduciaries of any such Plans should consult with their counsel before acquiring WES common units, WES preferred units or WES Operating debt securities.

In considering an investment in WES common units, WES preferred units or WES Operating debt securities with any portion of the assets of an employee benefit plan, a fiduciary of the employee benefit plan should consider, among other things, whether the investment is in accordance with the documents and instruments governing the employee benefit plan and the applicable provisions of ERISA, the Code or any applicable Similar Law relating to the fiduciary’s duties to the employee benefit plan, including, without limitation:

Prohibited Transaction Issues

Section 406 of ERISA and Section 4975 of the Code prohibit ERISA Plans from engaging in specified transactions involving “plan assets” with parties that, with respect to the ERISA Plans, are “parties in interest” under ERISA or “disqualified persons” under the Code (collectively “Parties in Interest”), unless an exemption is available. A Party in Interest who engages in a non-exempt prohibited transaction may be subject to excise taxes and other penalties and liabilities under ERISA and Section 4975 of the Code.

The acquisition and/or holding of securities by an ERISA Plan with respect to which WES. WES Operating or any underwriter or dealer are considered a Party in Interest may constitute or result in a direct or indirect prohibited transaction under Section 406 of ERISA and/or Section 4975 of the Code, unless the securities are acquired and held in accordance with an applicable statutory, class or individual prohibited transaction exemption. In this regard, the U.S. Department of Labor has issued prohibited transaction class exemptions, or PTCEs, that may provide exemptive relief for direct or indirect prohibited transactions resulting from the acquisition, holding and, if applicable, conversion of securities. These class exemptions include, without limitation, PTCE 75-1 (respecting specified transactions involving employee benefit plans and broker-dealers, reporting dealers and banks); PTCE 84-14, as amended, (respecting transactions directed by independent qualified professional asset managers); PTCE 90-1 (respecting certain investments by insurance company pooled separate accounts); PTCE 91-38 (respecting certain investments by bank collective investment funds); PTCE 95-60 (respecting certain life insurance company general accounts); and PTCE 96-23 (respecting certain transactions determined by in-house asset managers). In addition, Section 408(b)(17) of ERISA and Section 4975(d)(20) of the Code each provide relief from the prohibited transaction provisions of ERISA and

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Section 4975 of the Code for certain transactions, provided that (i) if the issuer of the securities or any underwriters or dealers is a Party in Interest, it is a Party in Interest solely by reason of providing services to an ERISA Plan or being an affiliate of such a service provider and does not have or exercise any discretionary authority or control or render any investment advice with respect to the assets of the ERISA Plan involved in the transaction and (ii) the ERISA Plan pays no more than adequate consideration in connection with the transaction. Each of these statutory exemptions and PTCEs contains conditions and limitations on its application and do not provide relief from the self-dealing prohibitions under ERISA and Section 4975 of the Code. Thus, the fiduciaries of an employee benefit plan that is considering acquiring and/or holding WES common units, WES preferred units or WES Operating debt securities in reliance on any of these, or any other, exemptions should carefully review the exemption and consult with their counsel to confirm that it is applicable. There can be no, and neither WES nor WES Operating provide any, assurance that any of these exemptions or any other exemption will be available with respect to the acquisition or holding of the securities, or that all of the conditions of any such exemptions will be satisfied.

Because of the foregoing, none of WES common units, WES preferred units or WES Operating debt securities may be purchased or held (or converted to equity securities, in the case of any convertible debt) by any person investing “plan assets” of any employee benefit plan, unless such purchase and holding (or conversion, if any) will not constitute a non-exempt prohibited transaction under ERISA or the Code or similar violation of any applicable Similar Laws.

Representations

Accordingly, by acceptance of WES common units, WES preferred units or WES Operating debt securities, or any interest therein, each purchaser and subsequent transferee of such common units, preferred units or debt securities will be deemed to have represented and warranted that either (i) no portion of the assets used by such purchaser or transferee to acquire and hold such common units, preferred units or debt securities (or any interest therein) constitutes assets of any employee benefit plan or (ii) the acquisition and holding (and any conversion, if applicable) of such common units, preferred units or debt securities (or any interest therein) by such purchaser or transferee will not constitute a non-exempt prohibited transaction under Section 406 of ERISA or Section 4975 of the Code or similar violation under any applicable Similar Laws. In addition, the person making the decision to acquire WES common units, WES preferred units or WES Operating debt securities on behalf of an ERISA Plan (the “Plan Fiduciary”) will be deemed to have represented and warranted by its acceptance thereof that none of WES, WES Operating or any underwriter or dealer offering such units or securities, or any of their respective affiliates, has acted as the ERISA Plan’s fiduciary, or has been relied upon for any advice or recommendations, with respect to the Plan Fiduciary’s decision to acquire, hold, sell, convert or provide any consent with respect to such common units, preferred units or debt securities.

The foregoing discussion of issues arising for employee benefit plan investments under ERISA, the Code and applicable Similar Laws is general in nature and is not intended to be all inclusive, nor should it be construed as legal advice. In light of the complexity of these rules and the excise taxes, penalties and liabilities that may be imposed on persons involved in non-exempt prohibited transactions or other violations, plan fiduciaries contemplating a purchase of WES common units, WES preferred units or WES Operating debt securities should consult with their own counsel regarding the consequences of such purchase under ERISA, the Code and Similar Laws. The sale of any WES common units, WES preferred units or WES Operating debt securities by or to any employee benefit plan is in no respect a representation by the issuer thereof or any of its affiliates or representatives that such an investment meets all relevant legal requirements with respect to investments by such employee benefit plans generally or any particular employee benefit plan, or that such an investment is appropriate for such employee benefit plans generally or any particular employee benefit plan.

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